US4013846A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Piston loudspeaker
Assignee: 3M Co
•
Filing: 1976-06-01
•
Granted: 1977-03-22
•
Expires: 1996-06-01
Abstract
Abstract An electroacoustic loudspeaker having a rigid, light-weight diaphragm and a substantially closed loop magnet support of a magnetically permeable material having a channel-shaped cross-section and supported adjacent and spaced from the diaphragm with the open side of the channel facing the diaphragm. The magnet support carries a pair of magnets magnetized and positioned with opposite poles in spaced facing relation and a voice coil is secured to the diaphragm and lies in the gap between the magnets.
Inventors
- 👤 William G. Krawczak
- 👤 William M. Mularie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:21
CPC Classifications
H; H04; H04R; H04R9/00; H04R9/06; H04R9/02; H04R9/025
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
129 words
A loudspeaker comprising: a rigid, light-weight diaphragm having broad front and rear faces, a magnetically permeable keeper having a channel-shaped cross-section and forming a substantially closed loop, means supporting said keeper adjacent and spaced from said rear face of said diaphragm with the open side of said channel facing said diaphragm, a pair of magnets formed of fine grain, high coercivity, permanent magnetic material and supported within said keeper channel, one along each side wall of said channel, said magnets extending around said substantially closed loop of said keeper and being magnetized and positioned with opposite poles in spaced facing relation, and a voice coil secured to said rear face of said diaphragm and positioned in the space between said magnets around said substantially closed loop of said keeper.
Claim 2
Dependent Claim
129 words
A loudspeaker comprising: a rigid, light-weight diaphragm having broad front and rear faces, a magnetically permeable keeper having a channel-shaped cross-section and forming a substantially closed loop, means supporting said keeper adjacent and spaced from said rear face of said diaphragm with the open side of said channel facing said diaphragm, a pair of magnets formed of fine grain, high coercivity, permanent magnetic material and supported within said keeper channel, one along each side wall of said channel, said magnets extending around said substantially closed loop of said keeper and being magnetized and positioned with opposite poles in spaced facing relation, and a voice coil secured to said rear face of said diaphragm and positioned in the space between said magnets around said substantially closed loop of said keeper.
Claim 3
Dependent Claim
18 words
The loudspeaker of claim 1 wherein said broad front and rear faces of said diaphragm are generally planar.
Claim 4
Dependent Claim
16 words
The loudspeaker of claim 1 wherein said diaphragm is formed of a low density cellular plastic.
Claim 5
Dependent Claim
35 words
The loudspeaker of claim 3 wherein said substantially closed loop of said keeper is spaced from the center of said diaphragm approximately one-third of the distance from the center to the edge of said diaphragm.
Claim 6
Dependent Claim
23 words
The loudspeaker of claim 3 wherein said front face of said diaphragm is formed with sound dispersing projections to aid in sound distribution.
Claim 7
Dependent Claim
48 words
The loudspeaker of claim 3 wherein said diaphragm and said means supporting said keeper are joined at the edges of said diaphragm to form an integral structure and wherein the edges of said integral structure are formed for support by the T-bar supports of a T-bar suspended ceiling.
Claim 8
Dependent Claim
24 words
The loudspeaker of claim 1 wherein said magnets are formed of fine grain, high coercivity magnetic material dispersed in a flexible non-magnetic immobilizing matrix.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-03-21 | 1980-09-20 | 1981-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-21 | 1984-09-20 | 1985-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-21 | 1988-09-20 | 1989-03-22 | $7700.00 | Window Closed / Lapsed |